Apparatus system and method for acquisition of on-demand system information

ABSTRACT

The present disclosure relates to a mobile terminal and base station and respective operation methods. The mobile terminal comprises circuitry, which in operation, determines a condition for requesting on-demand a transmission of other system information; performs a random access procedure; and receives via broadcast a system information message including the on-demand requested other system information. The system information request message of the random access procedure includes an information element with a bit-pattern conforming to a specific format with at least a part of the bit-pattern for requesting the other system information. And the contention resolution message of the random access procedure includes the same, or the same part of the bit-pattern for detecting collisions during the random access procedure.

BACKGROUND Technical Field

The present disclosure relates to a mobile terminal performing systeminformation acquisition in a wireless communication system comprising atleast one base station configured with a serving cell. The systeminformation includes minimum information and other system information.The mobile terminal transmits on-demand a request message to the basestation. This request message requests the base station to transmit theother system information.

Description of the Related Art

Currently, the 3rd Generation Partnership Project (3GPP) focuses on thenext release (Release 15) of technical specifications for the nextgeneration cellular technology, which is also called fifth generation(5G) or new radio (NR).

At the 3GPP Technical Specification Group (TSG) Radio Access network(RAN) meeting #71 (Gothenburg, March 2016), the first 5G study item,“Study on New Radio Access Technology” involving RAN1, RAN2, RAN3 andRAN4 was approved and the study has laid the foundation of the Release15 work item (WI) which will define the first standard.

One objective of 5G new radio (NR) is to provide a single technicalframework addressing all usage scenarios, requirements and deploymentscenarios defined in 3GPP TSG RAN TR 38.913 v14.1.0, “Study on Scenariosand Requirements for Next Generation Access Technologies,” December 2016(available at www.3gpp.org). These include at least enhanced mobilebroadband (eMBB), ultra-reliable low-latency communications (URLLC),massive machine type communication (mMTC).

For example, eMBB deployment scenarios may include indoor hotspot, denseurban, rural, urban macro and high speed; URLLC deployment scenarios mayinclude industrial control systems, mobile health care (remotemonitoring, diagnosis and treatment), real time control of vehicles,wide area monitoring and control systems for smart grids; mMTC mayinclude the scenarios with large number of devices with non-timecritical data transfers such as smart wearables and sensor networks.

Another objective is the forward compatibility, anticipating future usecases/deployment scenarios. The backward compatibility to Long TermEvolution (LTE) is not required, which facilitates a completely newsystem design and/or the introduction of novel features.

BRIEF SUMMARY

One non-limiting and exemplary embodiment enables improving the systeminformation acquisition in a wireless communication system comprising amobile terminal and a base station with a serving cell. Anothernon-limiting exemplary embodiment strives to reduce the (control)signaling overhead to the acquisition of on-demand other systeminformation. And a further exemplary embodiment strives to improve theflexibility in the acquisition of on-demand other system information.

In one embodiment, the techniques disclosed here feature a mobileterminal for performing system information acquisition in a wirelesscommunication system comprising at least one base station configuredwith a serving cell. The system information includes minimum systeminformation and other system information.

The mobile terminal comprises a processor and a transceiver. With this,the mobile terminal is adapted to determine a condition for requestingon-demand a transmission of other system information; perform a randomaccess procedure including: transmitting a random access preamble signal(msg1), receiving a random access response message (msg2), transmittinga system information request message (msg3) for the other systeminformation, and receiving a contention resolution message (msg4); andreceive via broadcast a system information message including theon-demand requested other system information.

The system information request message (msg3) includes an informationelement with a bit-pattern conforming to a specific format with at leasta part of the bit-pattern for requesting the other system information,and the contention resolution message (msg4) includes the same, or thesame part of the bit-pattern for detecting collisions during the randomaccess procedure.

It should be noted that general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

Additional benefits and advantages of the disclosed embodiments will beapparent from the specification and Figures. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 depicts a block diagram of a mobile terminal, and a base stationin a wireless communication system;

FIG. 2 illustrates a sequence diagram of system information acquisitionaccording to an exemplary implementation of the first embodiment in a3GPP NR deployment scenario;

FIG. 3 shows an exemplary request and response message configuration forother system information in an exemplary implementation of the firstembodiment in a 3GPP NR deployment scenario;

FIG. 4 depicts another exemplary request and response messageconfiguration for other system information in an exemplaryimplementation of the first embodiment in a 3GPP NR deployment scenario;

FIG. 5 illustrates a sequence diagram of system information acquisitionaccording to an exemplary implementation of the first embodiment in a3GPP NR deployment scenario;

FIG. 6 shows a timing diagram of two mobile terminals (i.e., UE1 andUE2) performing system acquisition in a first example of the secondaspect in a 3GPP NR deployment scenario;

FIG. 7 depicts a timing diagram of two mobile terminals (i.e., UE1 andUE2) performing system acquisition in a second example of the secondaspect in a 3GPP NR deployment scenario; and

FIG. 8 depicts a timing diagram of two mobile terminals (i.e., UE1 andUE2) performing system acquisition in a third example of the secondaspect in a 3GPP NR deployment scenario.

DETAILED DESCRIPTION

As summarized in one of the technical reports for the NR study item(3GPP TSG TR 38.801 v2.0.0, “Study on New Radio Access Technology; RadioAccess Architecture and Interfaces,” March 2017), the fundamentalphysical layer signal waveform will be based on Orthogonal FrequencyDivision Multiplexing (OFDM). For both downlink and uplink, OFDM withcyclic prefix (CP-OFDM) based waveform is supported. Discrete FourierTransformation (DFT) spread OFDM (DFT-S-OFDM) based waveform is alsosupported, complementary to CP-OFDM waveform at least for eMBB uplinkfor up to GHz.

One of the design targets in NR is to enhance the user's mobility withminimizing the interruption of ongoing traffic if any, and at the sametime without increasing the user equipment power consumption. At RAN#78, RAN2 was tasked to investigate how the IMT-2020 requirement on Omshandover interruption time can be addressed for LTE and NR within theRel-15 time frame. At a first step, handover procedure in LTE has beenadopted as a baseline design in NR. There are ongoing discussions in3GPP working groups regarding what functionalities need to be added ormodified for NR mobility enhancement.

The term “downlink” refers to communication from a higher node to alower node (e.g., from a base station to a relay node or to a UE, from arelay node to a UE, or the like). The term “uplink” refers tocommunication from a lower node to the higher node (e.g., from a UE to arelay node or to a base station, from a relay node to a base station, orthe like). The term “sidelink” refers to communication between nodes atthe same level (e.g., between two UEs, or between two relay nodes, orbetween two base stations).

In 3GPP NR, the acquisition of system information has greatly improvedover mechanisms known from the former versions of, for example, the LTEstandards. For example, system information handling discussed in chapter7.3 of 3GPP TS 38.300 V15.1.0: “NR; NR and NG-RAN Overall Description”March 2018. Only a brief discussion will follow herein below.

Overview

According to the standardization of 3GPP NR, System Information (SI) isdivided into Minimum SI and Other SI. Minimum SI is periodicallybroadcast and comprises basic information required for initial accessand information for acquiring any other SI broadcast periodically orprovisioned on-demand, i.e., scheduling information. The Other SIencompasses everything not broadcast in the Minimum SI and may either bebroadcast, or provisioned in a dedicated manner, either triggered by thenetwork or upon request from the UE.

For a cell/frequency that is considered for camping by the UE, the UE isnot required to acquire the contents of the minimum SI of thatcell/frequency from another cell/frequency layer. This does not precludethe case that the UE applies stored SI from previously visited cell(s).If the UE cannot determine the full contents of the minimum SI of a cell(by receiving from that cell or from valid stored SI from previouscells), the UE shall consider that cell as barred. In case of BandwidthAdaptation (BA), the UE only acquires SI on the active Bandwidth Part(BWP).

Scheduling

The Minimum SI is transmitted over two different downlink channels usingdifferent messages (MasterInformationBlock andSystemInformationBlockType1). The term Remaining Minimum SI (RMSI) isalso used to refer to SystemInformationBlockType1 (SIB1). Other SI istransmitted in SystemInformationBlockType2 (SIB2) and above.

For UEs in RRC_IDLE and RRC_INACTIVE, the request triggers a randomaccess procedure and is carried over MSG3 unless the requested SI isassociated to a subset of the PRACH resources, in which case MSG1 can beused. When MSG1 is used, the minimum granularity of the request is oneSI message (i.e., a set of SIB s), one RACH preamble and/or PRACHresource can be used to request multiple SI messages and the gNBacknowledges the request in MSG2. When MSG 3 is used, the gNBacknowledges the request in MSG4.

The Other SI may be broadcast at a configurable periodicity and for acertain duration. The Other SI may also be broadcast when it isrequested by UE in RRC_IDLE/RRC_INACTIVE.

Each cell on which the UE is allowed to camp broadcasts at least somecontents of the Minimum SI, while there may be cells in the system onwhich the UE cannot camp and do not broadcast the Minimum SI.

SI Modification

Change of system information only occurs at specific radio frames, i.e.,the concept of a modification period is used. System information may betransmitted a number of times with the same content within amodification period, as defined by its scheduling. The modificationperiod is configured by system information.

When the network changes (some of the) system information, it firstnotifies the UEs about this change, i.e., this may be done throughout amodification period. In the next modification period, the networktransmits the updated system information. Upon receiving a changenotification, the UE acquires the new system information from the startof the next modification period. The UE applies the previously acquiredsystem information until the UE acquires the new system information.

Paging is used to inform UEs in RRC_IDLE, RRC_INACTIVE and inRRC_CONNECTED about a system information change. If the UE receives suchpaging message, it knows that the system information (other than forETWS/CMAS) will change at the next modification period boundary.

In addition to the 3GPP NR technical standard TS 38.300, which reflectsthe development efforts of RAN #79, the system information handling hasalso been more recently discussed by the TSG Radio Access Network(TSG-RAN) Work Group 2 (WG2) which is briefly summarized in thefollowing:

SI Provided by Broadcast

The scheduling information for other SI includes SIB type, validityinformation, periodicity, and SI-window information in minimum SIirrespective of whether other SI is periodically broadcasted or providedon demand

-   -   The scheduling information for other SI is provided in SIB1    -   SIB type: broadcast or on-demand

If minimum SI indicates that a SIB is not broadcasted, then UE does notassume that this SIB is a periodically broadcasted in its SI-Window atevery SI-Period. Therefore, the UE may send an SI request to receivethis SIB. After sending the SI request, for receiving the requested SIB,UE monitors the SI window of requested SIB in one or more SI periods ofthat SIB.

Msg3 Based SI Request Method

UE determines successful Msg3 based on reception of Msg4. It remains forfurther study (FFS) as to what details of the Msg4 content are used toconfirm successful Msg3. This is to be discussed initially by CP.

Preamble(s) for SI request using Msg3 based Method are not reserved.Further, RRC signaling is used for SI request in Msg3. It is also leftfor further study (FFS) by ASN.1 work as to how RRC signaling indicatesthe requested SI/SIB details. Temporary C-RNTI received in Msg2 is usedfor Msg4 reception.

On-Demand SI Request

UE ID is not included in MSG3. For contention resolution UE MAC performssame as other cases and check the contention resolution MAC CE againstthe transmitted request (common RACH procedure in MAC)

One indicator in SystemInformationBlockType1 (SIB1) indicates whether anSI message is currently broadcast or not. The indication is valid untilthe end of the modification period. UE cannot infer whether this is atemporary broadcast of an on demand SI or a periodic broadcast SI.

SI Modification

Like LTE, the SI change/update is indicated to UEs through paging.RRC_IDLE and RRC_INACTIVE UEs shall monitors for SI update notificationin its own paging occasion every DRX cycle. RRC_CONNECTED UE monitorsfor SI update notification in any paging occasion (if the UE is providedwith common search space to monitor paging in connected).

In NR, the LTE concept of modification period for SI update handling isadopted. SI update indication included in paging message is supported(this can be revisited if the DCI design allows the SI update indicationand scheduling of a paging message in parallel). SI update indicationincluded in DCI is supported.

If UE receives SI update indication in paging, then UE acquires theupdated SI at the next modification period boundary assuming NWbroadcasts updated SI (even if the updated SI is on-demand SI).

Present Disclosure

Considering the above, the present disclosure has been conceived withthe understanding that that system information acquisition can befurther improved.

Particularly, utilizing the random access procedure in 3GPP NR foracquiring on-demand system information has some advantages as well asdrawbacks on the (control) signaling overhead for the wirelesscommunication system. The drawbacks resulting from this feature are atthe focus of the present disclosure.

On the one hand, the random access procedure is a well-understoodmechanism, which allows a mobile terminal to start immediately signaling(control) information with a base station. Specifically the randomaccess procedure can be engaged by the mobile terminal irrespective ofwhether it is in a RRC CONNECTED, RRC_IDLE or RRC_INACTIVE state. Inother words, the random access procedure for acquiring on-demand systeminformation can be used immediately after power-up.

On the other hand, the random access procedure introduces a considerable(control) signaling overhead. As will be discussed in further detailbelow, the random access procedure (i.e., contention-based random accessprocedure) is well understood to include a sequence of four messages(henceforth: msg1, msg2, msg3 and msg4). This sequence of four messagesis designed to enable a reliable signaling between mobile terminal andbase station, however, at the expense of a non-negligible (control)signaling overhead.

Recognizing these shortcomings, the present disclosure strives toimprove the system information acquisition in the wireless communicationsystem.

Non-limiting and exemplary embodiments enable reducing in the wirelesscommunication system the (control) signaling overhead resulting from therandom access procedure, specifically in situations where collisionsoccur between different mobile terminal's system information acquisitionattempts. In particular, the present disclosure tries to avoid anyunnecessary re-transmissions triggered by unsuccessful (i.e.,contentious) system information acquisition attempts.

For a comprehensive discussion of the advantages provided by the presentdisclosure, two different scenarios are described in further detailbelow.

In a first scenario, emphasis is laid on the fact that the cause for the(control) signaling overhead, i.e., the understanding that collisions inthe random access procedure have occurred, is eliminated. For this, therandom access procedure assumes, when acquiring system information, adifferent understanding of what collisions are. Thereby, additional(control) signaling is avoided that would normally result inre-transmissions as prescribed by the contention resolution mechanism inthe random access procedure.

In second scenario, emphasis is laid on the fact that the effectresulting in the (control) signaling overhead, i.e., there-transmissions as prescribed by the contention resolution mechanism,can be removed for the system information acquisition without affectingthe functional capability of the wireless communication system. Forthis, specific conditions are defined where it is not necessary toinvoke the content resolution mechanism in the random access procedure,thus also avoiding the additional (control) signaling.

In other words, the two different scenarios of the present disclosureare linked by a cause-and-effect relationship in that they both solvethe common technical problem of avoiding additional (control) signaling,unless ultimately necessary in the wireless communication system. The(control) signaling overhead resulting from the contention resolutionmechanism in the random access procedure is accordingly reduced.

The random access procedure (more specifically the contention-basedrandom access procedure) includes four steps which are briefly discussedin the following:

In a first step, a random access preamble signal, i.e., msg1, (in-short:preamble) is transmitted by a mobile terminal to the base station. Thepreamble is randomly selected by the mobile terminal from all availableor a specific subset of available preambles and/or is transmitted on allavailable or specifically selected physical random access channel,PRACH, resources.

Due to restrictions on the number of available preambles and/or PRACHresources (the resource in a specific time and spectrum frequency), anddue to the fact that the mobile terminal autonomously starts the randomaccess procedure, contentions between preamble transmissions from twodifferent mobile terminals cannot be avoided. In other words, thewireless communication system cannot prevent a situation where twodifferent mobile terminals are transmitting a same preamble on a samePRACH resource.

Additionally and even more importantly, the base station cannotdistinguish between such contentious transmissions as they result fromtwo different mobile terminals transmitting a same preamble on a samePRACH resource. Thus, the base station requires external knowledge todiscover such contentious transmissions.

In a second step, a random access response message, i.e., msg2,(in-short: response) is transmitted by the base station to the mobileterminal. The response generally includes parameters for connectionestablishment, such as for example a timing advance to be applied to themobile terminal's uplink configuration, as well as a scheduling grant,which permits the mobile terminal to transmit the subsequent message inthe uplink.

In a third message, a dedicated message, i.e., msg3, is transmitted bythe mobile terminal to the base station using the scheduling grant. Forthe sake of brevity, reference is made in the following only to thesystem information request message, i.e., a message which serves thededicated purpose of a mobile terminal signaling to the base station therequest for the transmission of (specific) on-demand system information,for example a (specific) on-demand system information message.

In an exemplary implementation, the system information request messagemay include a request for acquiring a (specific) on-demand systeminformation message, e.g., a request for an on-demand transmittedmessage comprising system information block type 4-6. In general, thesystem information request message follows a specific format specifiedby the radio resource control, RRC, layer, for example, for an RRCSystem Information Request message.

As the two different mobile terminals causing the contentioustransmissions in step 1, receive the same response in step 2, they willboth transmit a dedicated messages, i.e., msg3, using the indicatedscheduling grant. Accordingly, the two dedicated messages are alsoreceived by the base station as contentions transmissions, i.e., asmessages conflicting or overlapping in time and spectrum frequency, and(if at all) only one of the dedicated messages can be successfullydecoded by the base station.

Even more importantly, it has been discovered that at specific timings(e.g., during radio frames and/or sub-frames with specific numbers),there is a high likelihood that the two different mobile terminals,causing the contentious transmissions in step 1, are both transmittingas msg3 a request for acquiring a same on-demand system informationmessage. Thus, there may be situations in which the base stationreceives two conflicting or overlapping system information requestmessage transmissions requesting the same or different on-demand systeminformation message.

Again and more importantly, the base station can only recognize one ofthe system information request messages from the mobile terminal whosesignal is stronger.

In a fourth message, a connection resolution message, i.e., msg4, istransmitted by the base station to the mobile terminal(s). This messageis designed to put the mobile terminal in a situation where it candetect whether or not the base station intends to comply with therequest set out in the dedicated message transmitted in msg3. In otherwords, this msg4 comprises information which uniquely references msg3 orthe mobile terminal generating same msg3, and for this reason may servethe purpose of resolving situations with contentious transmissions.

Notably, the capability of the mobile terminal to discover and thusresolve a situation with contentious transmissions depends on theinformation transmitted in the dedicated message, i.e., msg3.Particularly, this capability ties in with the question of whether ornot the msg3 includes additionally or only information which is uniquebetween all mobile terminals.

Conventionally, this msg3 is formatted to include, for example, a uniquerandom value (i.e., random value information element) in the context ofa RRC connection request. This unique random value then ensures that twomsg3s are never the same (i.e., are unique), even if they originate fromtwo different mobile terminals utilizing the same scheduling grant frommsg2.

Then, the base station generates the contention resolution message bycopy-and-pasting (or echoing) the unique information from the msg3,thereby permitting the mobile terminal to discover whether it hassucceeded in placing its request set out in the dedicated messagetransmitted as msg3.

Only when a mobile terminal discovers in msg4 the unique informationwhich it has transmitted with msg3, then it can conclude that msg3 wastransmitted successfully to the base station. Should the mobile terminalhave been un-successful, the random access procedure prescribes itstarts again with the re-transmission of the random access preamblesignal, i.e., msg1. Thereby, situations with contentious transmissionsare resolved.

Now, in the context of the present disclosure it is recognized that acontention resolution is not always favorable in the context of systeminformation acquisition. In particular, there are situations where it isun-necessary for a mobile terminal to start again with there-transmission of the random access preamble signal, i.e., msg1, afteran un-successful contention resolution. In other words, for somesituation the (control) signaling overhead resulting from the contentionresolution in the random access procedure can be avoided.

As mentioned above, in the context of system information acquisitionthere exist situations where two different mobile terminals arerequesting the same on-demand system information message via the msg3.Then, in such a situation, it is not decisive for the mobile terminal toknow whether itself (or the other one of the two different mobileterminal) has successfully placed its request set out in the systeminformation request message or whether it is pre-scribed to re-transmitssame system information request message in result to a contentioustransmission.

As soon as it is ensured that the base station responding with msg4 hasreceived the request for transmitting the desired system informationmessage, the requests of both of the two different mobile terminals aremet.

In other words, neither the cause (i.e., the understanding thatcollisions in the random access procedure have occurred) nor the effect(i.e., the re-transmissions as prescribed by the contention resolutionmechanism) justifies the resulting (control) signal overhead. Rather, assoon as the base station complies with the requests of both of the twodifferent mobile terminals, it is no longer necessary to apply thecontention resolution mechanism of the random access procedure.

First Scenario

FIG. 1 illustrates a block diagram of a wireless communication systemincluding a mobile terminal 110 (also referred to as user equipment,UE), and a base station 160 (also referred to as g Node B, gNB). Thisblock diagram is used for describing the mechanism depicted in FIG. 2 ,namely the first scenario where the cause for the (control) signalingoverhead is eliminated.

The wireless communication system of the block diagram permits themobile terminal 110 to acquire system information, particularly othersystem information (which is not minimum system information) broadcastedon-demand from the base station 160 with a serving cell. Accordingly,both the mobile terminal 110 and the base station 160 take an activerole in the system information acquisition.

In general, there exist multiple conditions when a processor 120 of themobile terminal 110 determines (see step S01 in FIG. 2 ) that it has ademand for and thus wants to request on-demand the transmission of othersystem information from the base station 160.

For example, such a condition occurs, when the processor 120 detects apower-up event in the serving cell or a cell selection/reselection eventto the serving cell. Such a condition can also occur, when the processor110 is recovering from a loss of coverage event for the serving cell.Additionally, such a condition may also occur, when the processor 120determines that a validity timer for the other system information hasexpired in the serving cell. In any one of these exemplary conditions,the processor 120 does not have a valid copy of the other systeminformation.

Provided the processor 120 has determined a condition to requeston-demand the transmission of other system information, it proceeds witha transceiver 130 of the mobile terminal 110 performing (see step S02 inFIG. 2 ) a random access procedure.

In the random access procedure, the transceiver 130 is firsttransmitting a random access preamble signal (see msg1 of S02 in FIG. 2) to the base station 160. Then, the transceiver 130 is receiving fromthe base station 160 a random access response message (see msg2 of S02in FIG. 2 ). Thereafter, the transceiver 130 is transmitting to the basestation 160 a system information request message (see msg3 of S02 inFIG. 2 ) for the other system information. And finally, the transceiver130 is receiving from the base station 160 a contention resolutionmessage (see msg4 of S02 in FIG. 2 ).

Provided the mobile terminal 110 has successfully placed a request forthe other system information with the base station 160, it proceeds withthe transceiver 130 receiving (see step S03 in FIG. 2 ) via broadcast asystem information message including the on-demand requested othersystem information.

In order to the determine whether the mobile terminal 110 hassuccessfully placed a request for the other system information with thebase station 160, it determines whether the following two conditions aremet:

-   -   1) the system information request message (see msg3 of S02 in        FIG. 2 ) includes an information element with a bit-pattern        conforming to a specific format with at least a part of the        bit-pattern for requesting the other system information, and    -   2) the contention resolution message (see msg4 of S02 in FIG. 2        ) includes the same, or the same part of the bit-pattern for        detecting collisions during the random access procedure.

The first of the two conditions ensures that the mobile terminal 110places a commonly understood request for the other system informationwith the base station 160. For this purpose, the request is carried inan information element (e.g., of an RRC message) in a specificbit-pattern. Importantly, the bit pattern conforms to a specific format(e.g., a standardized format). The specific format prescribes that atleast a part of the bit pattern is used for requesting the other systeminformation. Thereby, the specific format permits unambiguouslyidentifying at the base station 160 the requested other systeminformation.

The second of the two conditions ensure that the mobile terminal 110 isnotified whether the request for the other system information with thebase station 160 is successfully placed. For this purpose, thecontention resolution message includes the same bit-pattern (as a whole)or at least the same part of the bit-pattern prescribed by the specificformat for requesting the other system information. Importantly, in caseof the same bit-pattern or the same part of the bit-pattern are includedin the contention resolution message, the mobile terminal 110 can detectcollisions (better, the absence thereof) during the random accessprocedure.

Notably, with these two conditions the collision detection can be madeon the bit-pattern basis or the part of the bit-pattern prescribed bythe specific format. As all the requests for other system informationhave to conform to the same specific format, even when originating fromtwo different mobile terminals, then the collision detection alsoassumes a successful placement in case of contentious transmissions fromtwo different mobile terminals for the same request for other systeminformation. Even more importantly, due to the specific formatprescribing at least the part of the bit-pattern for the collisiondetection, the (control) signaling overhead is advantageously reduced.

These two conditions are exemplified in the detailed implementationsshown in FIGS. 3 and 4 .

FIGS. 3 and 4 depict in the top-most part exemplary bit-patterns andtheir specific formats for requesting the other system information. Thefirst of the two figures details an implementation where the specificformat prescribes that a part of the bit-pattern is used for requestingthe other system information. And, the second of the two figures detailsan implementation where the specific format prescribes that thebit-pattern (as a whole) is use for requesting the other systeminformation.

Particularly, for both the part of the bit-pattern and the bit-pattern(as a whole) the specific format defines a correspondence with requestsfor different types of system information messages (abbreviated as SImsg. 2 to 9). For example, the SI msg. 3 may denote the request totransmit, as part of the same system information message, the systeminformation blocks of types 4-6. In both implementations, both the partof the bit-pattern and the bit pattern is 8 bits and each one of the 8bits corresponds to a request for a different type of system informationmessage (e.g., the second bit is shown to correspond to SI msg. 3 andthe fourth bit is shown to correspond to the SI msg. 5).

With regard to the first of the two figures, it is shown that thespecific format prescribes that the part of the bit-pattern (i.e., the 8bits) for requesting the other system information message is located atthe start (beginning) in the bit-pattern (i.e., the total 40 bits). Thisis shown in the left corner of the top-most part of the figure.Alternatively part of the bit-pattern (i.e., the 8 bits) for requestingthe other system information message is located at the end (tail) in thebit-pattern (i.e., the total bits). This is shown in the right corner ofthe top-most part of the figure. Obviously the left and right corners ofthe top-most part of the figure depict alternative implementations forthe specific format as denoted by the term “or.”

It shall not go without saying that (also) in the first of the twofigures, it is also shown that the specific format prescribes that theremaining bits of the bit-pattern, excluding the bits forming the partof the bit-pattern for requesting the other system information, have azero value.

Irrespective of which of the specific formats are used, the bit-patternare included in an information element of an RRC message that resemblesthe system information request message (i.e., msg3 of S02 in FIG. 2 ).The information element can be the first information element in thesystem information request message or, more preferably the onlyinformation element in the system information request message (i.e.,msg3), as also depicted in the two figures.

For conformance reasons with the current definitions in the RRC layer of3GPP NR, it is advantageous when the bit-pattern has 40 bits. Thereby,the same sized MAC control element, CE, can be re-used as for thecontention resolution message (e.g., msg4) transmitted in response to aRRC connection establishment message (e.g., msg3). Particularly, thisprevents from necessitating different physical implementations for thecontention resolution mechanisms in the base station and/or mobilestation. Nevertheless, the bit-pattern may also only have a size of 8bits (or at least 8 bits) to accommodate all bits corresponding torequests for different types of system information messages (abbreviatedas SI msg. 2 to 9).

For clarification purpose, and to avoid confusions, the informationelement including the bit-pattern for requesting the other systeminformation is not the one for the mobile terminal identity (termed:ue-identity in RRC) and/or not the one for the random value (termed:randomValue in RRC).

As generally known from 3GPP NR, the information element including thebit-pattern is encoded in a MAC SDU, resulting in an additional 8 bitsencoding overhead at the start (beginning) of the MAC SDU, whichtogether with the MAC header forms a MAC PDU, as shown in the leftcorner of the bottom part of both of the two figures. The mobileterminal 110 transmits this MAC PDU then as msg3 to the base station160.

In response thereto, the detail implementations show, in the rightcorner of the bottom part of the two figures, that the mobile terminal110 receives from the base station 11 a MAC message as contentionresolution message, msg4, comprising a MAC header and a MAC CE. This MACCE is depicted including or excluding an encoding overhead of additional8 bits at the start (beginning) of the MAC CE.

Assuming for the sake of example, that the information element includesa bit pattern with a total size of 40 bits and that only a part of 8bits from the total 40 bits is prescribed by the specific format forrequesting other system information. Then the content resolutionmessage, msg4, can include either the same bit-pattern (as a whole)resulting in a MAC CE with a size of 48 bits, or the same part of thebit-pattern prescribed by the specific format resulting in a MAC CE witha size of 8 bits.

In the first case, the successful/unsuccessful reception of thecontention resolution message is determined by the processor 120checking whether the contention resolution message, msg4, includes only(i.e., exactly) a same bit-pattern as transmitted with the informationelement included in the system information request message, msg3.

In the second case, the successful/unsuccessful reception of thecontention resolution message is determined by the processor 120checking whether the contention resolution message, msg4, is a specialversion of the contention resolution message (i.e., a shortened version)specifically used to acknowledge the on-demand request for other systeminformation. Again, a shortened version does no longer conform toconventional MAC CE used in other contexts for contention resolution.

Additionally, the processor 120 is checking whether the msg4 includesonly the same part of the bit-pattern (prescribed by the specific formatfor requesting other system information) as transmitted with theinformation element included in the system information request message,msg3,

Assuming now for the sake of example, that the information elementincludes a bit pattern with a total size of (only) 8 bits and that thesebits are prescribed by the specific format for requesting other systeminformation. Then the content resolution message, msg4, can includeeither the same bit-pattern (as a whole) with zero-padding at the end toamount to a large size of, for example, again 48 bits, or can include(only) the same bit-pattern (as a whole) resulting in a MAC CE with asize of 8 bits.

In the first case, the successful/unsuccessful reception of thecontention resolution message is determined by the processor 120checking whether part (i.e., the non-zero-padded bits) of the contentionresolution message, msg4, include a same bit-pattern as transmitted withthe information element included in the system information requestmessage, msg3.

In the second case, the successful/unsuccessful reception of thecontention resolution message is determined by the processor 120checking whether the contention resolution message, msg4, is a specialversion of the contention resolution message (i.e., a shortened version)specifically used to acknowledge the on-demand request for other systeminformation. Again, a shortened version does no longer conform toconventional MAC CE used in other contexts for contention resolution.

Additionally, the processor 120 is checking whether the msg4 includes asame bit-pattern as transmitted with an information element included inthe system information request message, msg3, conforming to the specificformat for requesting the other system information.

Second Scenario

Equally the block diagram of FIG. 1 can be used for describing themechanism depicted in FIG. 5 , namely the second scenario where theeffect resulting in the (control) signaling overhead is removed withoutaffecting the system functionality.

Again, the wireless communication system of the block diagram permitsthe mobile terminal to acquire system information, particularly othersystem information (which is not minimum system information) broadcastedon-demand from the base station 160 with a serving cell.

In general, there exist multiple conditions when a processor 120 of themobile terminal 110 determines (see step S01 in FIG. 5 ) that it has ademand for and thus wants to request on-demand the transmission of othersystem information from the base station 160.

For sake of brevity, reference is made to the exemplary conditionsdiscussed above. Provided the processor 120 has determined a conditionto request on-demand the transmission of other system information, itproceeds with the transceiver 130 of the mobile terminal 110 performing(see step S02 in FIG. 5 ) a random access procedure.

In the random access procedure, the transceiver 130 is firsttransmitting a random access preamble signal (see msg1 of S02 in FIG. 5) to the base station 160. Then, the transceiver 130 is receiving fromthe base station 160 a random access response message (see msg2 of S02in FIG. 5 ). Thereafter, the transceiver 130 is transmitting to the basestation 160 a system information request message (see msg3 of S02 inFIG. 5 ) for the other system information. And finally, the transceiver130 is receiving from the base station 160 a contention resolutionmessage (see msg4 of S02 in FIG. 5 ).

Now differently from the above, this second scenario is concerned with asituation where, despite an unsuccessful reception of the contentionresolution message (indicated by the flash to msg4), it is dispensablefor the mobile terminal to start (begin) with the re-transmission of therandom access preamble signal (msg1) as prescribed by the random accessprocedure.

Specifically, it is recognized that the unsuccessful reception can bethe result from a conflicting request for other system information whichis directed to the same (or subset of same) types of system informationmessages.

For example, a conflicting transmission could be detected even where onemobile terminal unsuccessfully places a request for SI msg. 3 and asecond, different mobile terminal successfully places a request for SImsg. 3 and SI msg. 5. Then, even if the base station complies (only)with the successful request for SI msg. 3 and SI msg. 5, it would bedispensable for the unsuccessful mobile terminal to re-transmit thesystem information request (starting with msg1) as prescribed by therandom access procedure.

This, however, depends on the question whether it can obtain informationabout the scheduled SI messages from an additional source, differentfrom the msg4.

Importantly, it has been discovered that at specific timings (e.g.,during radio frames and/or sub-frames with specific numbers), there is ahigh likelihood for two different mobile terminals to request as msg3the same (or subset of same) types of system information messages. Atleast in these situations, the re-transmission of system informationrequests can be removed without affecting the performance of the system.Again for this, the unsuccessful mobile terminal has to be provided withinformation about the scheduled SI messages from an additional source.

For this purpose, in case of an unsuccessful reception (see flash inFIG. 5 ) of the contention resolution message, msg4, the mobile terminal110 performs as part of the random access procedure (see S02 in FIG. 5 )the following: First, the processor 130 suspends the re-transmission ofthe random access preamble signal, msg1. In other words, with suspendingthe re-transmission, the unsuccessful mobile terminal buys additionaltime to determine whether one of the above mention condition hasoccurred. In particular, the processor suspends the re-transmissionuntil the next time instance of the minimum system information.

As already apparent from the previous section, the minimum systeminformation is continuously broadcasted at specific periodic timeintervals and, hence, does not require rely on on-demand requests.Importantly, the minimum system information (specifically theSystemInformationBlock Type 1, SIB1) includes an indicator whichindicates whether an other system information message is currentlybroadcast or not with a validity until the end of the modificationperiod.

In the context of the present disclosure, it is assumed that the basestation 160 indicates with this indicator in the minimum systeminformation, e.g., SIB1, which other system information, e.g., whichtypes of system information messages it schedules for broadcasting untilthe end of the modification.

Coming back to the example, when the second different mobile terminalsuccessfully places a request for SI msg. 3 and SI msg. 5, then therespective indicators in the minimum system information, e.g., SIB1,will give away information on the scheduled SI messages to all mobileterminals, not the one mobile terminal successfully placing its request.

By receiving this minimum system information all mobile terminals caninfer which of the other system information is scheduled fortransmission.

In line with the above, after suspending the re-transmission, thetransceiver 120 receives (see msg4′ in FIG. 5 ) at the next timeinstance, the minimum system information at the next time instance.

And further, the processor 130 determines (see step S02′ in FIG. 5 )based on the received minimum system information, if the requested othersystem information is scheduled for transmission via broadcastindependent of the re-transmission thereof. In such a situation, there-transmission as prescribed by the random access procedure isdispensable.

Having determined that the requested other system information isscheduled for transmission, the transceiver 120 proceeds with receiving(see step S03 in FIG. 5 ) via broadcast a system information messageincluding the on-demand requested other system information.

In summary, due to the separate (additional) reception operation (seemsg4′ in FIG. 5 ) of minimum system information, the mobile terminal 110can discover situations where, despite the fact of having beenunsuccessful in placing the request for other system information, themobile terminal can dispense with the re-transmissions as prescribed bythe random access procedure.

Thus, according to this second scenario the effect resulting in the(control) signaling overhead is removed without affecting the systemfunctionality.

Referring again to the general description of FIG. 1 , the advantageousimplementation in 3GPP NR deployment scenario includes that the systeminformation request message, msg3, is a radio resource control, RRC,message, preferably with the information element having a total size of40 bits. And the advantageous implementation additionally includes thatthe contention resolution message, msg4, is a medium access control,MAC, control element, CE, preferably having a total size of 48 bits.Thereby, compatibility with existing formats in the random accessprocedure (e.g., the RRC connection request) can be ensured.

It goes without saying that also the system information can be acquiredby the mobile terminal in one of the RRC_CONNECTED, RRC_IDLE, andRRC_INACTIVE state.

Second Aspects

Referring now to a different second aspect of the present disclosure.This second aspect stands separately from the previous description, evenif it also relates to system information acquisition. More specifically,also here the system information also includes minimum systeminformation and other system information.

Notably the difference over the previous description lies in the factthat the second aspect concerns itself with the object to increase theflexibility in acquiring the system information. This increase inflexibility may result in a reduced delay, i.e., in a reception ofon-demand requested other system information ahead of schedule, and/ormay result in reduced (control) signaling overhead. In any case, thefollowing aspect ties in with the specification of the modificationperiod.

Generally, the modification period is well understood to describe a timeperiod during which a mobile terminal is expected to only once acquirethe system information. This modification period is introduced tosafeguard the power consumption, for example, of mobile terminals in theRRC_IDLE or RRC_INACTIVE state. Should the mobile terminal be expectedto wake up and acquire system information more frequently, then thiswould result in a negative impact on the mobile terminal's powerconsumption.

However, there are situations where the mobile terminal is, in onemodification period, requesting on-demand other system information,however is required by due to system constraints, to only receive,during the next modification, the on-demand requested other systeminformation. This introduces a considerable delay upon the systeminformation acquisition within the wireless communication system.

In this situation, this aspect increases the flexibility by permittingthe system to more flexibly broadcast other system information, as shownin the implementation of FIG. 6 .

FIG. 6 depicts a timing diagram of two mobile terminals (i.e., UE1 andUE2) performing system acquisition in a first example of this secondaspect in a 3GPP NR deployment scenario. In this first example, awireless communication system is shown comprising two mobile terminals(i.e., UE1 and UE2) and a base station with a serving cell.

At the start of the first modification period (modification period #1),the other system information, e.g., the system information message 5(SI_5), is not broadcasted. This is shown by the respective indicator inthe minimum system information, e.g., system information block type 1(SIB1), having a value of zero (“broadcast=0”).

Thus, a mobile terminal with a demand for such other system information(e.g., SI_5) has to proceed with requesting on-demand the transmissionthereof. This shall be discussed in further detail with regard to thesystem information acquisition performed by the second mobile terminal,i.e., UE2 as shown in this FIG. 6 .

This mobile terminal, UE2, determines, at the time point indicated withthe arrow in FIG. 6 , that a condition has occurred for on-demandrequesting other system information (e.g., SI_5). For sake of brevity,reference is made to the exemplary conditions discussed above.

It goes without saying that the determining the on-demand requestingcondition, includes that the mobile terminal acquires the minimum systeminformation (e.g., SIB1) and basis its determination on this receivedminimum system information (e.g., SIB1). Only when the mobile terminaldetermines that the other system information (e.g., SI_5) is transmittedon-demand (“broadcast=0”), then it actually begins with the randomaccess procedure.

The mobile terminal UE2 performs a random access procedure including:transmitting a random access preamble message (msg1), receiving a randomaccess response message (msg2), transmitting a system informationrequest message (msg3) for the other system information, and receiving acontention resolution message (msg4).

In a conventional configuration, the mobile terminal would have to waituntil the next modification period (e.g., modification period #2) toreceive via broadcast a system information message including theon-demand requested other system information (e.g., SI_5). In thisparticular case, this modification period is also carrying changed (new)other system information (e.g., SI_5), which however has no impact onthe first example.

Different therefrom, in this example, the mobile terminal, UE2, canreceive ahead of schedule.

For this purpose, the mobile terminal UE2 is configured to (again)re-acquire, within a current modification period (e.g., modificationperiod #1) that is the same of the random access procedure, minimumsystem information (e.g., SIB1). Based on this re-acquired minimumsystem information (e.g., SIB1), the mobile terminal determines whetherthe on-demand requested other system information (e.g., SI_5) is beingtransmitted ahead of the next modification period (e.g., “broadcast=1”).And the mobile terminal receives the on-demand requested other systeminformation (e.g., SI_5) included in the system information messagebeing transmitted ahead of the next modification period (ahead ofmodification period #2).

Notably, the current (old) not the changed (new) other systeminformation (e.g., SI_5) is broadcasted in this modification period(e.g., modification period #1). Thus, it will have to receive in thenext modification period again the changed (new) other systeminformation (e.g., SI-5). Despite the repetition, this exampleadvantageously allows for a consistent implementation of themodification period with the current standardization.

In summary, this first example provides for the advantages of havingless specification impact; and allowing the UE2 obtain SI_5 immediately.There is no impact on other mobile terminals (UE1). These advantagescome at a price of the following disadvantages: SI request overheadincreases for a soon changed (new) SI; which in effect leads to morepower consumption for UE2 (needs to check the SIB1 in two in twocontinuous modification periods after requesting on-demand the othersystem information), and more SI broadcast overheads.

FIG. 7 depicts a timing diagram of two mobile terminals (i.e., UE1 andUE2) performing system acquisition in a second example of this secondaspect in a 3GPP NR deployment scenario. In this second example, awireless communication system is shown comprising two mobile terminals(i.e., UE1 and UE2) and a base station with a serving cell.

At the start of the first modification period (modification period #1),the other system information, e.g., the system information message 5(SI_5), is not broadcasted. This is shown by the respective indicator inthe minimum system information, e.g., system information block type 1(SIB1), having a value of zero (“broadcast=0”).

Thus, a mobile terminal with a current version of the other systeminformation (e.g., SI_5) would not have any incentive to proceed withacquiring again the transmission thereof. This however changes when themobile terminal is indicated a change (update) of the other systeminformation (e.g., SI_5). This shall be discussed in further detail withregard to the system information acquisition performed by the firstmobile terminal, i.e., UE1 as shown in this FIG. 7 .

For the sake of clarity, it is emphasized that the mobile terminal UE1already has a current version of the other system information (e.g.,SI_5). The mobile terminal UE1 may have received same by acquiringsystem information as discussed above, namely by first determiningwhether a condition for on-demand requesting other system information(e.g., SI_5) has occurred, and then performing the random accessprocedure. Finally, the mobile terminal UE 1 may have received theon-demand requested other system information (e.g., SI_5) as discussedabove.

Now, for the purpose of receiving changed (updated) other systeminformation, the mobile terminal UE1 receive a paging message (locatedin the paging occasion, PO, with number #i for the UE1). This pagingmessage indicates a change in the on-demand requested other informationmessage (e.g., “SI_5 change=true”). This paging message is received in acurrent modification period (modification period #1).

Then, the mobile terminal UE1 re-acquires, within a current modificationperiod that is the same of the received paging message (modificationperiod #1), every minimum system information (e.g., SIB1).

At the same time the mobile terminal, UE2, determines, at the time pointindicated with the arrow in FIG. 7 , that a condition has occurred foron-demand requesting other system information (e.g., SI_5).

It goes without saying that the determining the on-demand requestingcondition, includes that the mobile terminal acquires the minimum systeminformation (e.g., SIB1) and basis its determination on this receivedminimum system information (e.g., SIB1). Only when the mobile terminaldetermines that the other system information (e.g., SI_5) is transmittedon-demand (“broadcast=0”), then it actually begins with the randomaccess procedure.

The mobile terminal UE2 performs a random access procedure including:transmitting a random access preamble message (msg1), receiving a randomaccess response message (msg2), transmitting a system informationrequest message (msg3) for the other system information, and receiving acontention resolution message (msg4). And in this example the basestation successfully receives the on-demand system information requestfrom UE2, and thereafter changes the indicator of the requested othersystem information (e.g., SI_5) in the minimum system information.

Further, the mobile terminal UE1 is adapted to determine, based onre-acquired minimum system information (e.g., SIB1), whether the changedon-demand other system information (e.g., new SI_5) is being transmitted(“broadcast=1”) ahead of the next modification period (ahead of themodification period #2), due to the on-demand other system informationrequest sent by UE2.

Finally, both mobile terminals UE1 and UE2 receive the changed on-demandother system information (e.g., SI_5) included in the system informationmessage being transmitted ahead of the next modification period (aheadof modification period #2).

In summary, this second example provides for the advantages of enablingboth UE1 and UE2 to acquire the updated SI_5 immediately; resulting inless power consumption for UE2 (only needs to acquire the SI_5 once).These advantages come at a price of the following disadvantages:different UEs may operate based on different other system information,e.g., SI_5, in the same modification period; more SI broadcastoverheads; more power consumption for UE1; more specification impact.

FIG. 8 depicts a timing diagram of two mobile terminals (i.e., UE1 andUE2) performing system acquisition in a third example of this secondaspect in a 3GPP NR deployment scenario. In this third example, awireless communication system is shown comprising two mobile terminals(i.e., UE1 and UE2) and a base station with a serving cell.

At the start of the first modification period (modification period #1),the other system information, e.g., the system information message 5(SI_5), is not broadcasted. This is shown by the respective indicator inthe minimum system information, e.g., system information block type 1(SIB1), having a value of zero (“broadcast=0”).

Thus, a mobile terminal with a demand for such other system information(e.g., SI_5) would have to proceed with requesting on-demand thetransmission thereof. An alternative configuration shall be discussed infurther detail with regard to the system information acquisitionperformed by the second mobile terminal, i.e., UE2 as shown in this FIG.8 .

Particularly, it is assumed in the following that the mobile terminalUE2 only performs the random access procedure, as discussed before, whenthe following procedure is determined to be unsuccessful until the endof the current modification period.

Again, prior to performing the random access procedure, the mobileterminal UE2 receives, a paging message (located in the paging occasion,PO, with number #k for any UE) for a different mobile terminal (e.g.,UE1) indicating a change in the on-demand requested other systeminformation (e.g., SI_5) in a current modification period (modificationperiod #1).

Then, the mobile terminal UE2 determines, based on the paging message(e.g., located in PO #k) for the different mobile terminal (e.g., UE1),whether the on-demand requested other system information is beingtransmitted (i.e., “SI_5 change=true”) in the next modification period(modification period #2)

Finally, the mobile terminal UE2 skips performing the random accessprocedure, and subsequently, the mobile terminal UE2 receives theon-demand requested other system information (e.g., SI_5) included inthe system information message being transmitted in the nextmodification period (modification period #2).

In summary, this third example provides for the advantages of reducingthe number of on-demand SI request; thereby the SI broadcast overhead isreduced; and further a minimal specification impact is achieved. Theseadvantages come at a price of the following disadvantage: more latencyto acquire the missing SI.

The present disclosure can be realized by software, hardware, orsoftware in cooperation with hardware. Each functional block used in thedescription of each embodiment described above can be partly or entirelyrealized by an LSI such as an integrated circuit, and each processdescribed in the each embodiment may be controlled partly or entirely bythe same LSI or a combination of LSIs. The LSI may be individuallyformed as chips, or one chip may be formed so as to include a part orall of the functional blocks. The LSI may include a data input andoutput coupled thereto. The LSI here may be referred to as an IC, asystem LSI, a super LSI, or an ultra LSI depending on a difference inthe degree of integration.

However, the technique of implementing an integrated circuit is notlimited to the LSI and may be realized by using a dedicated circuit, ageneral-purpose processor, or a special-purpose processor. In addition,a FPGA (Field Programmable Gate Array) that can be programmed after themanufacture of the LSI or a reconfigurable processor in which theconnections and the settings of circuit cells disposed inside the LSIcan be reconfigured may be used. The present disclosure can be realizedas digital processing or analogue processing. If future integratedcircuit technology replaces LSIs as a result of the advancement ofsemiconductor technology or other derivative technology, the functionalblocks could be integrated using the future integrated circuittechnology. Biotechnology can also be applied.

According to a first aspect, a mobile terminal is disclosed forperforming system information acquisition in a wireless communicationsystem comprising at least one base station configured with a servingcell. The system information includes minimum system information andother system information.

The mobile terminal comprises a processor and a transceiver. With this,the mobile terminal is adapted to determine a condition for requestingon-demand a transmission of other system information; perform a randomaccess procedure including: transmitting a random access preamble signal(msg1), receiving a random access response message (msg2), transmittinga system information request message (msg3) for the other systeminformation, and receiving a contention resolution message (msg4); andreceive via broadcast a system information message including theon-demand requested other system information.

The system information request message (msg3) includes an informationelement with a bit-pattern conforming to a specific format with at leasta part of the bit-pattern for requesting the other system information,and the contention resolution message (msg4) includes the same, or thesame part of the bit-pattern for detecting collisions during the randomaccess procedure.

According to a second aspect, which can be combined with the firstaspect, the information element is the first information element in thesystem information request message (msg3).

According to a third aspect, which can be combined with the first orsecond aspect, the information element is the only information elementin the system information request message (msg3).

According to a fourth aspect, which can be combined with the first tothird aspect, the information element is not mobile terminal identityinformation element and/or not a random value information element.

According to a fifth aspect, which can be combined with the first tofourth aspect, the information element with a bit-pattern conforming tothe specific format comprises at least 8 bits, preferably 40 bits.

According to a sixth aspect, which can be combined with the first tofifth aspect, the specific format defines, for the part of thebit-pattern of the information element, a correspondence with requestsfor different types of system information messages.

According to a seventh aspect, which can be combined with the sixthaspect, the part of the bit-pattern of the information element is 8bits, and each of the 8 bits corresponds to a request for a differenttype of a system information message,

According to an eighth aspect, which can be combined with the sixth orseventh aspect, the specific format prescribes that the part of thebit-pattern, preferably the 8 bits, are located at the start or at theend in the bit pattern.

According to a ninth aspect, which can be combined with the sixth toeighth aspect, the specific format prescribes that all remaining bits inthe bit pattern of the information element, except those of the part ofthe bit-pattern, have a zero value.

According to a tenth aspect, which can be combined with the first toninth aspect, the mobile terminal begins receiving the systeminformation message including the on-demand requested other systeminformation depending on the bit-pattern in the contention resolutionmessage (msg4).

According to an eleventh aspect, a mobile terminal is disclosed forperforming system information acquisition in a wireless communicationsystem comprising at least one base station configured with a servingcell. The system information including minimum system information andother system information.

The mobile terminal comprises: a processor and a transceiver adapted todetermine a condition for requesting on-demand a transmission of othersystem information; perform a random access procedure including:transmitting a random access preamble signal (msg1), receiving a randomaccess response message (msg2), transmitting a system informationrequest message (msg3) for the other system information, and receiving acontention resolution message (msg4); and receive via broadcast a systeminformation message including the on-demand requested other systeminformation.

In case of an unsuccessful reception of the contention resolutionmessage (msg4), the mobile terminal performing a random access procedureincluding: suspending the re-transmission of the random access preamblesignal (msg1) until the next time instance of the minimum systeminformation, receiving, at the next time instance, the minimum systeminformation, and determining, based on the received minimum systeminformation, if the requested other system information is scheduled fortransmission via broadcast independent of the re-transmission thereof.

According to a twelfth aspect, which can be combined with the first toeleventh aspect, the successful/unsuccessful reception of the contentionresolution message (msg4) is determined by at least one of:

-   -   checking whether the contention resolution message (msg4)        includes only a same bit-pattern as transmitted with the        information element included in the system information request        message (msg3) conforming to the specific format for requesting        the other system information, and    -   checking whether the contention resolution message (msg4) is a        special version of the contention resolution message used to        acknowledge the on-demand request for other system information,        and whether the msg4 includes only the same part of the        bit-pattern as transmitted with the information element included        in the system information request message (msg3), and    -   checking whether part of the contention resolution message        (msg4) includes a same bit-pattern as transmitted with the        information element included in the system information request        message (msg3) conforming to a specific format for requesting        the other system information, and    -   checking whether the contention resolution message (msg4) is a        special version of the contention resolution message used to        acknowledge the on-demand request for other system information,        and whether the msg4 includes a same bit-pattern as transmitted        with an information element included in the system information        request message (msg3) conforming to the specific format for        requesting the other system information.

According to a thirteenth aspect, which can be combined with the firstto twelfth aspect, the system information request message (msg3) is aradio resource control, RRC, message, preferably with the informationelement having a total size of 40 bits.

According to a fourteenth aspect, which can be combined with the firstto thirteenth aspect, the contention resolution message (msg4) is amedium access control, MAC, control element, CE, preferably having atotal size of 48 bits.

According to a fifteenth aspect, which can be combined with the first tofourteenth aspect, for performing the system information acquisition,the mobile terminal is in one of the RRC_CONNECTED, RRC_IDLE, andRRC_INACTIVE state.

According to a sixteenth aspect, which can be combined with the first tofifteenth aspect, the condition for requesting on-demand thetransmission of the other system information includes at least one of:detecting a power-up event in or a cell selection/reselection event tothe serving cell, recovering from a loss of coverage event for theserving cell, determining that a validity timer for the other systeminformation has expired.

According to a seventeenth aspect, a base station is disclosed in awireless communication system enabling a mobile terminal to performsystem information acquisition with the base station configured with aserving cell. The system information including minimum systeminformation and other system information,

The base station comprises: a processor and a transceiver. With this,the base station is adapted to perform a random access procedureincluding: receiving a random access preamble signal (msg1),transmitting a random access response message (msg2), receiving a systeminformation request message (msg3) for other system information, andtransmitting a contention resolution message (msg4); and to transmit viabroadcast a system information message including the on-demand requestedother system information.

The system information request message (msg3) includes an informationelement with a bit-pattern conforming to a specific format with at leasta part of the bit-pattern for requesting the other system information,and the contention resolution message (msg4) includes the same, or thesame part of the bit-pattern for detecting collisions during the randomaccess procedure.

According to an eighteenth aspect, which can be combined with theseventeenth aspect, the information element is the first informationelement in the system information request message (msg3).

According to a nineteenth aspect, which can be combined with theseventeenth or eighteenth aspect, the information element is the onlyinformation element in the system information request message (msg3).

According to a twentieth aspect, which can be combined with theseventeenth to nineteenth aspect, the information element is not mobileterminal identity information element and/or not a random valueinformation element.

According to a twenty-first aspect, which can be combined with theseventeenth to twentieth aspect, the information element with abit-pattern confirming with the specific format comprises at least 8bits, preferably 40 bits.

According to a twenty-second aspect, which can be combined with theseventeenth to twenty-first aspect, the specific format defines, for asubset of bits in the bit-pattern of the information element, acorrespondence with requests for different types of system informationmessages.

According to a twenty-third aspect, which can be combined with thetwenty-second aspect, the subset of bits in the bit-pattern of theinformation element is 8 bits, and each of the 8 bits corresponds to arequest for a different type of a system information message.

According to the twenty-fourth aspect, which can be combined with thetwenty-second or twenty-third aspect, the specific format prescribesthat the subset of bits, preferably the 8 bits, are located at the startor at the end in the bit pattern.

According to a twenty-fifth aspect, which can be combined with thetwenty-second to twenty-fourth aspect, the specific format prescribesthat all remaining bits in the bit pattern of the information element,except those of the subset of bits, have a zero value.

According to the twenty-sixth aspect, which can be combined with theseventeenth to twenty-fifth aspect, the base station begins transmittingthe system information message including the on-demand requested othersystem information depending on the bit-pattern in the contentionresolution message (msg4).

According to a twenty-seventh aspect, a method is disclosed forperforming system information acquisition by a mobile terminal in awireless communication system comprising at least one base stationconfigured with a serving cell. The system information including minimumsystem information and other system information.

The method comprises the steps of: determining a condition forrequesting on-demand a transmission of other system information;performing a random access procedure including: transmitting a randomaccess preamble signal (msg1), receiving a random access responsemessage (msg2), transmitting a system information request message (msg3)for the other system information, and receiving a contention resolutionmessage (msg4); and receiving via broadcast a system information messageincluding the on-demand requested other system information.

The system information request message (msg3) includes an informationelement with a bit-pattern conforming to a specific format with at leasta part of the bit-pattern for requesting the other system information,and the contention resolution message (msg4) includes the same, or thesame part of the bit-pattern for detecting collisions during the randomaccess procedure.

According to a twenty-eight method, a method is disclosed for performingsystem information acquisition by a mobile terminal in a wirelesscommunication system comprising at least one base station configuredwith a serving cell. The system information including minimum systeminformation and other system information.

The method comprises the steps of: determining a condition forrequesting on-demand a transmission of other system information;performing a random access procedure including: transmitting a randomaccess preamble signal (msg1), receiving a random access responsemessage (msg2), transmitting a system information request message (msg3)for the other system information, and receiving a contention resolutionmessage (msg4); and receiving via broadcast a system information messageincluding the on-demand requested other system information.

In case of an unsuccessful reception of the contention resolutionmessage (msg4), performing a random access procedure includes:suspending the re-transmission of the random access preamble signal(msg1) until the next time instance of the minimum system information,receiving, at the next time instance, the minimum system information,and determining based on the received minimum system information, if therequested other system information is scheduled for transmission viabroadcast independent of the re-transmission thereof.

According to a twenty-ninth aspect, a method for a base station isdisclosed to enable a mobile terminal to perform system informationacquisition in a wireless communication system with the base stationconfigured with a serving cell. The system information including minimumsystem information and other system information.

The method comprises the steps of: performing a random access procedureincluding: receiving a random access preamble signal (msg1),transmitting a random access response message (msg2), receiving a systeminformation request message (msg3) for other system information, andtransmitting a contention resolution message (msg4); and transmittingvia broadcast a system information message including the on-demandrequested other system information.

The system information request message (msg3) includes an informationelement with a bit-pattern conforming to a specific format with at leasta part of the bit-pattern for requesting the other system information,and the contention resolution message (msg4) includes the same, or thesame part of the bit-pattern for detecting collisions during the randomaccess procedure.

According to a thirtieth aspect, a mobile terminal is disclosed forperforming system information acquisition in a wireless communicationsystem comprising at least one base station with a serving cell. Thesystem information includes minimum system information and other systeminformation.

The mobile terminal comprises a processor and a transceiver. With this,the mobile terminal is adapted to determine a condition for on-demandrequesting other system information, to perform a random accessprocedure including: transmitting a random access preamble message(msg1), receiving a random access response message (msg2), transmittinga system information request message (msg3) for the other systeminformation, and receiving a contention resolution message (msg4), andto receive via broadcast a system information message including theon-demand requested other system information.

Particularly, the mobile terminal is adapted, as part of determining theon-demand requesting condition, to acquire the minimum systeminformation and to determine that the other system information beingrequested is transmitted on-demand.

Further, the mobile terminal is adapted, as part of receiving the systeminformation message, to re-acquire, within a current modification periodthat is the same of the random access procedure, minimum systeminformation, to determine, based on the re-acquired minimum systeminformation whether the on-demand requested other system information isbeing transmitted ahead of the next modification period, and to receivethe on-demand requested other system information included in the systeminformation message being transmitted ahead of the next modificationperiod.

According to a thirty-first aspect, a mobile terminal is disclosed forperforming system information acquisition in a wireless communicationsystem comprising at least one base station with a serving cell. Thesystem information includes minimum system information and other systeminformation.

The mobile terminal comprises a processor and a transceiver. With this,the mobile terminal is adapted to determine a condition for on-demandrequesting other system information, to perform a random accessprocedure including: transmitting a random access preamble message(msg1), receiving a random access response message (msg2), transmittinga system information request message (msg3) for the other systeminformation, and receiving a contention resolution message (msg4), andto receive via broadcast a system information message including theon-demand requested other system information.

Particularly, the mobile terminal is adapted, as part of receiving thesystem information message, to receive a paging message indicating achange in the on-demand requested other system information in a currentmodification period, to re-acquire, within a current modification periodthat is the same of the received paging message, minimum systeminformation, to determine, based on re-acquired minimum systeminformation, whether the changed on-demand other system information isbeing transmitted ahead of the next modification period, and to receivethe changed on-demand other system information included in the systeminformation message being transmitted ahead of the next modificationperiod.

According to a thirty-second aspect, a mobile terminal is disclosed forperforming system information acquisition in a wireless communicationsystem comprising at least one base station with a serving cell. Thesystem information includes minimum system information and other systeminformation.

The mobile terminal comprises a processor and a transceiver. With this,the mobile terminal is adapted, to determine a condition for on-demandrequesting other system information, to perform a random accessprocedure including: transmitting a random access preamble message(msg1), receiving a random access response message (msg2), transmittinga system information request message (msg3) for the other systeminformation, and receiving a contention resolution message (msg4), andto receive via broadcast a system information message including theon-demand requested other system information.

Particularly, the mobile terminal is adapted, prior to performing therandom access procedure, to receive a paging messages for a differentmobile terminal indicating a change in the on-demand requested othersystem information in a current modification period, to determine, basedon the paging message for the different mobile terminal, whether theon-demand requested other system information is being transmitted in thenext modification period, to skip performing the random accessprocedure, and to receive the on-demand requested other systeminformation included in the system information message being transmittedin the next modification period.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. An integrated circuit for controlling a base station to enable amobile terminal to acquire system information including minimum systeminformation and other system information, the integrated circuitcomprising: processing circuitry and transceiver circuitry, which, inoperation performs a random access procedure including: receiving arandom access preamble signal from the mobile terminal, transmitting arandom access response message to the mobile terminal, receiving, fromthe mobile terminal, a system information request message requestingon-demand transmission of the other system information, and transmittinga contention resolution message to the mobile terminal; and transmitsvia broadcast a system information message including the on-demandrequested other system information; wherein the system informationrequest message includes an information element with a bit-patternconforming to a specific format with at least a part of the bit-patternfor requesting the other system information, and wherein the contentionresolution message includes the same, or the same part of thebit-pattern, for detecting collisions during the random accessprocedure.
 2. The integrated circuit according to claim 1, wherein theinformation element is the first information element in the systeminformation request message, and/or wherein the information element isthe only information element in the system information request message,and/or wherein the information element is not mobile terminal identityinformation element and/or not a random value information element,and/or the information element with the bit-pattern confirming to thespecific format comprises at least 8 bits.
 3. The integrated circuitaccording to claim 1, wherein the specific format defines, for a subsetof bits in the bit-pattern of the information element, a correspondencewith requests for different types of system information messages, andwherein the subset of bits in the bit-pattern of the information elementis 8 bits, and each of the 8 bits corresponds to a request for adifferent type of a system information message, and further wherein thespecific format prescribes that the subset of bits are located at thestart or at the end in the bit pattern, and even further, wherein thespecific format prescribes that all remaining bits in the bit pattern ofthe information element, except those of the subset of bits, have a zerovalue.
 4. The integrated circuit according to claim 1, wherein theprocessing circuitry and transceiver circuitry, in operation beginstransmitting the system information message including the on-demandrequested other system information depending on the bit-pattern in thecontention resolution message.